The 33884 Switch monitoring interface is a monolithic silicon integrated circuit (IC) to perform switch monitoring functions. The device provides an efficient interface between an electrical switch and a low-voltage microprocessor.
Pin definition
The 33884 provides pull-up and pull-down currents for switch contacts while monitoring input voltage levels. When appropriate static discharge capacitors are used at the input, all inputs are transient protected. There are four modes of operation: Sleep, Normal, polling, and polling + INT timer.
Simplified application diagram
Polling and timer mode are similar, except timer mode adds an interrupt that is sent to the microprocessor when a switch is detected to be off, or when an internal interrupt timer times out. The interrupt is eventually sent to the microprocessor. All modes of operation can be easily programmed through serial Peripheral interface (SPI) control.
33884 Simplified Block Diagram
Features
● Full Operation with 7.0 V ≤ VPWR ≤ 26 V, Limited Operation with 5.5 V ≤ VPWR ≤ 7.0V
● Input Voltage Range: -14 V to 40 V
● Interface Directly to Microprocessors Using SPI Protocol
● Wake Up on Change of Monitored Switch Status
● The Programmable Wetting Current
● Four Switch-to-Ground Switches
● Six (Fixed Function) Inputs Monitoring Six Switch-to-Ground Switches
● Two (Fixed Function) Inputs Monitoring Two Switch-to-Battery Switches
● Quiescent Current in Sleep Mode ≤ 10 µA
● Reset Input Defaults the Device to Sleep Mode
● Pb-Free Packaging Designated by Suffix Code EG
Typical application
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